This invention relates to a moving body measuring device for detecting state quantities of a moving body, and particularly to an image processing device for measuring traffic flows for detecting state quantities such as a traffic amount, a speed, an inter-vehicle distance, a density, an occupancy ratio, a traffic jam length, and a time required for passing a specified interval in automobile traffic flows.
As one of the moving body measuring devices, a development has been performed for the image processing device for measuring traffic flows, utilizing a TV camera, and measuring a traffic information of vehicles. FIG. 20 is a block diagram showing construction of a conventional image processing device for measuring traffic flows described in "A study on the measurement of two-dimensional movement of traffic" by Inoue et al, the proceedings of the 17th Image Technology Conference (1986), 16-13, p.p. 295 to 298. In FIG. 20, a reference numeral 1 designates an image taking machine, for instance, a TV camera, 2, a TV camera controlling circuit for controlling the TV camera 1, 3, a frame memory for receiving digitized image signals, 4, a window setting circuit for setting a sampling area of a vehicle, 5, a vehicle detecting circuit, 6, a vehicle running position detecting circuit, 7, a vehicle moving amount detecting circuit, and 8, a vehicle information measuring circuit.
Next, explanation will be given to the operation. The TV camera 1 takes an image of a running vehicle at an arbitrary frame interval, controlled by the TV camera controlling circuit 2. The frame memory 3 receives data digitized from image signals of the TV camera 1. The window setting circuit 4 sets a window of a size of a vehicle on a road, on a screen. The vehicle detecting circuit 5 detects the vehicle by sampling a characteristic of the vehicle such as a horizontal line or a vertical line thereof based on a domain set by the window setting circuit 4. The vehicle running position detecting circuit 6 detects a running position of the vehicle detected by the vehicle detecting circuit 5, on the screen, and the vehicle moving amount detecting circuit 7 compares the running position with another running position of the vehicle in a preceding frame, detects a moving amount of the vehicle on the screen, and transmits it to the window setting circuit 4. The window setting circuit 4 moves the window according to the moving amount. The vehicle is tracked by repeating the above operation. The tracking is finished at the time point when the vehicle is out of the screen, and the vehicle information measuring circuit 8 measures the speed of the vehicle, the inter-vehicle distance between the vehicle and a foregoing vehicle and the like.
Since the conventional moving body measuring device or the image processing device for measuring traffic flows, is composed as above, an inter-frame tracking treatment is necessary and, therefore, the construction is complicated. Furthermore, when the vehicle detecting cannot be performed by a noise or an influence of the other vehicles, the device can not track the vehicle, and the measuring accuracy is deteriorated. Furthermore, when there are a plurality of vehicles on the screen, the conventional device can only track a single vehicle.
Furthermore, the conventional moving body measuring device is constructed to detect the vehicle by sampling a spatial characteristic of the vehicle on the screen image such as the horizontal line or the vertical line. Therefore, the sampling of the vehicle cannot be performed adequately when a noise such as a horizontal line or a vertical line of a road surface pattern or a tire mark, is introduced in the background of the window, and a successive measuring treatment is in failure.